US secret choppers played key role in bin Laden raid

AP, WASHINGTON

Secret until now, stealth helicopters may have been key to the success of the Osama bin Laden raid. But the so-far-unexplained crash of one of the modified Black Hawks at the scene apparently compromised at least some of the aircraft’s secrets.

The two choppers evidently used radar-evading technologies, plus noise and heat suppression devices, to slip across the Afghan-Pakistan border, avoid detection by Pakistani air defenses and deliver an assault team of two dozen Navy SEALs into the al-Qaeda leader’s lair. Photos of the lost chopper’s wrecked tail are circulating online — proving it exists and also exposing sensitive details.

US President Barack Obama traveled on Friday to the home base, at Fort Campbell, Kentucky, of the elite Army pilots who flew the daring mission. They are members of the 160th Special Operations Aviation Regiment, nicknamed the Night Stalkers.

The reason one of the helicopters crash landed at the bin Laden compound has not been disclosed, but Daniel Goure, a defense specialist at the Lexington Institute think tank, said on Friday it might be explained by the unusual aerodynamics resulting from the aircraft’s modifications.

“It could be much more difficult to fly, particularly at slow speed and landing than you would expect from a typical Black Hawk,” Goure said.

DIFFICULT

The US military’s first stealth aircraft, the now-defunct F-117 fighter jet, was notoriously difficult to handle in flight, officials have said.

Night Stalker pilots also fly other, publicly acknowledged versions of the Black Hawk that are specially equipped with advanced navigation systems, plus devices allowing for low-level and all-weather flight, day or night. Those are rigged to permit occupants to “fast rope” from the helicopter as it hovers just off the ground — a technique used in the bin Laden assault.

Many aspects of stealth technology have been known for decades, including the use of angled aircraft edges and composite materials to make aircraft less visible on radar. The Army began a program to build a new class of helicopter with stealth technology in 1992. Known as the RAH-66 Comanche, it was canceled in 2004, in part to speed up development of drone aircraft.

Bill Sweetman, editor-in-chief of Defense Technology International and a long-time student of stealth aircraft development, said the biggest secret behind the stealth helicopter is simply that it existed.

“There was obviously a fairly high risk that you were going to compromise it one way or another the minute you used it,” he said in an interview.

The decision to use the helicopters reflected the extraordinary stakes involved in eliminating bin Laden, the world’s most-wanted terrorist. It is not known whether the choppers have been used in earlier Special Operations raids, but Dick Hoffman, a former Navy SEAL and now a defense analyst at the Rand Corp think tank, said he had never before heard of their existence.

Hoffman said in a telephone interview that the apparent stealth technology on the choppers boosted the raid’s chances for success.

“Getting into the target area undetected is hugely important, especially with these terrorist targets and militia targets,” he said.

He added that the SEAL team did not arrive at the Abbottabad compound in Pakistan in complete silence, since a resident in the same town was writing on Twitter during the raid that he could hear one or more helicopters and wondered what was happening.